Hello,
I allways loved class A amps, but it's allways problem to get all heatsinks needed (mostly because their high price), so I designed my amp like alephx which can work in class AB. Both output halves are biased to 1A, which can drive my 8 ohm speakers 20Wrms in class A, but circuit is able to run more power in class AB. I know I made some sins like complementary differential input stage etc. But the question is - what do you think about it and what would you make other way?

The amp is running for 4 months and I'm very satisfied with results (sorry no measurements). I'm going to integrate 4 chanels to one chassis and use active crossover for my speakers.

Attached schematic is very simplified so here are some details : for thermal stability I change current biasing diff pairs (this sulution took me some time to develop, but works and it's simple). Source resistors on output pairs (IRFP240 & IRFP9240) are 0R47 and currently I have 16 output transistors per chanel. In my future project (4 chanels) I'd like to run only 4 devices (minimum for this circuit) per chanel.

So, what do you think?

Nelson Pass

20th September 2005 08:48 PM

Looks great. Congratulations.

:cool:

DarkOne

21st September 2005 02:01 PM

Thanks Mr. Pass

B.L.

22nd September 2005 09:53 AM

Actual schematic please.

No problems with DC offset?

DarkOne

22nd September 2005 10:44 AM

2 Attachment(s)

No problems with DC, as can be seen on actual schematic, there are 4 resistors from both outputs to each CCS (like in AlephX). Currently I have 30mV between outputs and 150mV to ground.

LBHajdu

26th September 2005 10:23 PM

Itís a very nice amp and truly simple ! Could you comment on the sound (maybe a comparison to something else)? What rail voltage are you running them at? If others want to try building it you should post the component values.

DarkOne

26th September 2005 10:47 PM

It's hard for me to compare, because I haven't had opportunity to compare to other amps on the same gear. Currently I have Canton LE103 speakers, which I heard playing on Krell amp, but there was different source, than I have, so hard to tell. Within few months I'll compare amp on Dynaudio BM6 with Meridian (there will be a pair of golden ears with me, so we'll see).
According to my ears the amp has very smooth sound, L/R localization is perfect, F/R localisation can't check, speakers are not so good and currently I don't have good source. Bass is strong and well controled.

Rail voltages are +-25V with 180mF capacitance

Send me an email for component values (I have them only in Eagle pcb format)

Originally posted by DarkOne It's hard for me to compare, because I haven't had opportunity to compare to other amps on the same gear. Currently I have Canton LE103 speakers, which I heard playing on Krell amp, but there was different source, than I have, so hard to tell. Within few months I'll compare amp on Dynaudio BM6 with Meridian (there will be a pair of golden ears with me, so we'll see).
According to my ears the amp has very smooth sound, L/R localization is perfect, F/R localisation can't check, speakers are not so good and currently I don't have good source. Bass is strong and well controled.

Rail voltages are +-25V with 180mF capacitance

Send me an email for component values (I have them only in Eagle pcb format)